Slot Machine With Symbol Sensor And Control Method Thereof

ABSTRACT

A slot machine repeatedly detects symbols displayed in the middle columns of display windows even after the respective rotatable reels are stopped, and judges whether or not the symbols displayed in the display windows are changed after all the rotatable reels are stopped.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to co-pending U.S. provisional patent application Ser. No. 60/929,030 filed on Jun. 8, 2007, and which is incorporated by reference herein for all purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a slot machine configured to execute games by use of game media such as coins, bills and the like, and to a control method thereof.

2. Description of Related Art

U.S. Pat. No. 4,138,114 discloses a slot machine configured to execute unit games (slot games) by rotating and stopping multiple rotatable reels each of which includes symbols that are printed on a circumferential surface thereof.

In a slot machine using multiple rotatable reels as represented by the above-mentioned slot machine, it is possible to easily change contents and layouts of symbols on the respective rotatable reels substantially by attaching, onto the circumferential surfaces of the respective rotatable reels, new reel bands that include symbols with new contents and layouts printed on surfaces thereof.

In the slot machine using the multiple rotatable reels, a decision as to whether or not a payout should be awarded is made according to the combination of the symbols on the circumferential surfaces of the respective reels viewable through display windows, the symbols aligned as a result of stopping rotation of the rotatable reels in a unit game. Accordingly, in the slot machine using the multiple rotatable reels, it is necessary to detect the symbol viewable through the display window for each of the rotatable reels after all of the rotatable reels are rotated and then stopped.

Concerning such detection of the symbols, U.S. Pat. No. 4,138,114 discloses a technique in which symbols and markings with binary codes for detecting the symbols are drawn on the respective rotatable reels.

Therefore, when changing the contents and the layouts of the symbols on the respective rotatable reels by attaching the above-mentioned reel bands to the respective rotatable reels according to U.S. Pat. No. 4,138,114, it is necessary to attach the reel bands accurately to the rotatable reels so as not to cause misalignment of positions of the symbols on the reel bands and positions of the markings on the rotatable reels.

When the reel bands are not attached to the rotatable reels accurately, the contents of the symbols detected by reading the binary codes of the markings after the rotatable reels are stopped do not match the contents of the symbols actually displayed in the display windows. Occurrence of such a mismatch may cause occurrence of an erroneous payout or nonoccurrence of a payout that should be made.

However, an operation to fit the reel bands accurately to the rotatable reels requires skill, and is extremely complicated. Accordingly, such an operation is not practical.

U.S. Pat. No. 4,074,258 discloses a device that detects a position of a movable member. In this device, multiple identification marks having different contents from each other are written with intervals on a strip-shaped scale connected to the movable member along the moving direction of the movable member. The device reads the identification marks optically in the course of movement of the movable member, and thereby detects a position of the movable member by using the contents of the identification marks thus read out.

However, the related art disclosed in U.S. Pat. No. 4,074,258 is for detecting the position of the strip-shaped scale itself after movement thereof, and hence does not have a relation with detection of symbols printed on a reel band.

Japanese Unexamined Patent Application Laid-open Publications Nos. 2003-803, H6-170033, and 2006-187529 disclose slot machines each including one or multiple reel bands, each of which has symbols drawn on the front surface, and bar codes indicating contents of the symbols drawn on the rear surface, and each of which is attached to the outer periphery of a rotatable reel.

Japanese Unexamined Patent Application Publication No. H6-246032 and Japanese Patent Publication No. 2772455 (Japanese Unexamined Patent Application Publication No. H6-277328) disclose slot machines each including information code marks indicating contents of symbols drawn on either the front surface or the rear surface of a reel band.

Japanese Unexamined Patent Application Publication No. 2002-35200 discloses a slot machine including reel bands in each of which a magnetic tape with information recorded therein is attached to the rear surface of the reel band, the information indicating contents of symbols.

All the related arts disclosed in these publications are merely for simply confirming with a readout result of barcodes, information code marks or information recorded on magnetic tapes that symbols matching a predetermined combination are actually displayed on display windows of a slot machine after stopping rotation of rotatable reels.

Accordingly, the related arts disclosed in these publications do not offer any effective countermeasures against a case where a user obtains a fraudulent payout by improperly (intentionally) rotating rotatable reels that has already stopped and thereby improperly aligning on display windows a combination of symbols for providing a payout.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a slot machine capable of detecting occurrence of an intentional rotating operation of a rotatable reel, even after the original rotating operation of the rotatable reel is stopped.

The first aspect of the present invention is a slot machine comprising: a rotatable reel including a plurality of symbols drawn on a peripheral surface thereof and being rotatable and stoppable; a display adapted to display part of the symbols; a sensor configured to repeatedly detect the symbols displayed on the display at least after a stop of the rotatable reel; and a controller configured to (a) execute a unit game for rotating and stopping the rotatable reel, (b) determine an outcome of the unit game according to one of the symbols detected by the sensor at a time point of the stop of the rotatable reel, and (c) judge whether or not the one of the symbols displayed on the display is changed after the stop of the rotatable reel, according to the symbols repeatedly detected by the sensor after the stop of the rotatable reel.

The second aspect of the present invention is a slot machine comprising: a rotatable reel being rotatable and stoppable; a reel band wound on a peripheral surface of the rotatable reel and having a plurality of symbols drawn on the reel band; a display adapted to display part of the symbols; a sensor configured to repeatedly detect the symbols displayed on the display at least after a stop of the rotatable reel; and a controller configured to (a) execute a unit game for rotating and stopping the rotatable reel, (b) determine an outcome of the unit game according to one of the symbols detected by the sensor at a time point of the stop of the rotatable reel, and (c) judge whether or not the one of the symbols displayed on the display is changed after the stop of the rotatable reel, according to the symbols repeatedly detected by the sensor after the stop of the rotatable reel.

The third aspect of the present invention is a slot machine comprising: a rotatable reel being rotatable and stoppable; a reel band wound on a peripheral surface of the rotatable reel and having a plurality of symbols drawn on the reel band; a display adapted to display part of the symbols; a sensor configured to repeatedly detect the symbols displayed on the display at least after a stop of the rotatable reel; and a controller configured to (a) execute a unit game for rotating and stopping the rotatable reel, (b) store the symbols repeatedly detected by the sensor after the stop of the rotatable reel and time points of detections of the symbols by the sensor linking each other, (c) determine an outcome of the unit game according to at least one of the symbols linked to a time point of the stop of the rotatable reel among the stored symbols, and (d) judge whether or not the at least one of the symbols displayed on the display is changed after the stop of the rotatable reel according to the stored symbols.

The fourth aspect of the present invention is a slot machine comprising: a rotatable reel being rotatable and stoppable; a reel band wound on a peripheral surface of the rotatable reel and having a plurality of symbols drawn on the reel band; a display adapted to display part of the symbols; a sensor configured to repeatedly detect the symbols displayed on the display at least after a stop of the rotatable reel; a removable memory storing the symbols repeatedly detected by the sensor after the stop of the rotatable reel and time points of detections of the symbols by the sensor linking each other; and a controller configured to (a) execute a unit game for rotating and stopping the rotatably reel, (b) determine an outcome of the unit game according to at least one of the symbols linked to a time point of the stop of the rotatable reel among the symbols stored in the memory, and (c) judge whether or not the at least one of the symbols displayed on the display is changed after the stop of the rotatable reel according to the symbols stored in the memory.

The fifth aspect of the present invention is a method of controlling a slot machine, the method comprising the steps of: executing a unit game for rotating and stopping a rotatable reel including a plurality of symbols drawn on a peripheral surface; displaying part of the symbols on a display; repeatedly detecting the symbols displayed on the display at least after a stop of the rotatable reel; determining an outcome of the unit game according to one of the symbols detected by the sensor at a time point of the stop of the rotatable reel; and judging whether or not the one of the symbols displayed on the display is changed after the stop of the rotatable reel, according to the symbols repeatedly detected by the sensor after the stop of the rotatable reel.

The sixth aspect of the present invention is a method of controlling a slot machine, the method comprising the steps of: executing a unit game for rotating and stopping a rotatable reel including a reel band wound on a peripheral surface of the rotatable reel and having a plurality of symbols drawn on the reel band; displaying part of the symbols on a display; repeatedly detecting the symbols displayed on the display at least after a stop of the rotatable reel; determining an outcome of the unit game according to one of the symbols detected by the sensor at a time point of the stop of the rotatable reel; and judging whether or not the one of the symbols displayed on the display is changed after the stop of the rotatable reel according to the symbols repeatedly detected by the sensor after the stop of the rotatable reel.

The seventh aspect of the present invention is a method of controlling a slot machine, the method comprising the steps of: executing a unit game for rotating and stopping a rotatable reel including a reel band wound on a peripheral surface of the rotatable reel and having a plurality of symbols drawn on the reel band; displaying part of the symbols on a display; repeatedly detecting the symbols displayed on the display at least after a stop of the rotatable reel; storing the symbols detected in the detecting step and time points of the detections linking each other; determining an outcome of the unit game according to at least one of the symbols linked to a time point of the stop of the rotatable reel among the stored symbols; and judging whether or not the at least one of the symbols displayed on the display is changed after the stop of the rotatable reel according to the stored symbols.

The eighth aspect of the present invention is a method of controlling a slot machine, the method comprising the steps of: executing a unit game for rotating and stopping a rotatable reel including a reel band wound on a peripheral surface of the rotatable reel and having a plurality of symbols drawn on the reel band; displaying part of the symbols on a display; repeatedly detecting the symbols displayed on the display at least after a stop of the rotatable reel; storing in a removable memory the symbols detected in the detecting step and time points of the detections; determining an outcome of the unit game according to at least one of the symbols linked to a time point of the stop of the rotatable reel among the symbols stored in the memory; and judging whether or not the at least one of the symbol displayed on the display is changed after the stop of the rotatable reel according to the symbols stored in the memory.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart showing procedure of processing to be executed by a slot machine according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the appearance of the slot machine according to the embodiment of the present invention.

FIG. 3 is a perspective view showing rotatable reels and a surrounding structure thereof according to the embodiment of the present invention.

FIG. 4 is a perspective view showing one of the rotatable reels and a surrounding structure thereof according to the embodiment of the present invention.

FIG. 5A is an explanatory view showing a front surface of a reel band according to the embodiment of the present invention.

FIG. 5B is an explanatory view showing a rear surface of the reel band according to the embodiment of the present invention.

FIG. 6 is a block diagram showing an electrical configuration of the slot machine according to the embodiment of the present invention.

FIG. 7 is an explanatory view showing an example of correspondence data according to the embodiment of the present invention.

FIG. 8 is a flowchart showing procedures of processing to be executed by the slot machine according to the embodiment of the present invention.

FIG. 9 is a block diagram showing an electrical configuration of a slot machine according to a first modified example of the embodiment of the present invention.

FIG. 10 is a block diagram showing an electrical configuration of a server according to the first modified example of the embodiment of the present invention.

FIG. 11 is a perspective view showing a rotatable reel and a surrounding structure thereof according to a second modified example of the embodiment of the present invention.

FIG. 12 is a perspective view showing a rotatable reel and a surrounding structure thereof according to a third modified example of the embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENT

FIG. 1 is a flowchart schematically showing processing to be executed by a slot machine 10 according to an embodiment of the present invention. First of all, an outline of the processing to be executed by the slot machine 10 will be described with reference to FIG. 1 to FIG. 3. FIG. 2 is a perspective view showing the appearance of the slot machine 10, and FIG. 3 is a perspective view showing rotatable reels 53 a to 53 c and a surrounding structure thereof. In Step S1, the slot machine 10 executes a unit game. The unit game is for rotating and stopping the rotatable reels 53 a to 53 c. Reel bands Q1 to Q3 are wound around the peripheral surfaces of the rotatable reels 53 a to 53 c, respectively. Although the front end and the back end of each of the reel bands Q1 to Q3 are bonded together, the reel bands Q1 to Q3 are not bonded to the rotatable reels 53 a to 53 c. However, as the reel bands Q1 to Q3 are wound around the rotatable reels 53 a to 53 c, when the rotatable reels 53 a to 53 c are rotated, the reel bands Q1 to Q3 are also rotated along with rotation of the rotatable reels 53 a to 53 c. Multiple symbols R1 are drawn on each of the reel bands Q1 to Q3. Some of the symbols drawn on the reel bands Q1 to Q3 are displayed on display windows 16 a to 16 c provided on a display 16. Accordingly, in the unit game, the scrolled symbols R1 are displayed on the display windows 16 a to 16 c as the rotatable reels 53 a to 53 c are rotated, and the stopped symbols R1 are displayed on the display windows 16 a to 16 c as the rotatable reels 53 a to 53 c are stopped. Three of the stopped symbols R1 are displayed on each of the display windows 16 a to 16 c. In other words, each of the display windows 16 a to 16 c is divided into an upper column, a middle column, and a lower column, and the stopped symbols R1 are displayed in the respective columns.

In Step S2, the slot machine 10 confirms an outcome of the unit game.

In Step S3, the slot machine 10 detects the symbols R1 displayed in the middle columns of the display windows 16 a to 16 c and stores the detected symbols R1 and a time point of detection, which are related to each other. A method of detecting the symbols R1 will be described later.

In Step S4, the slot machine 10 judges whether an error occurrence condition is satisfied according to the results obtained in Steps S2 and S3, the error occurrence condition being that any of the symbols R1 displayed on the display windows 16 a to 16 c is changed after the time point when all the rotatable reels 56 a to 56 c are stopped. In other words, the slot machine 10 judges, according to the results obtained in Steps S2 and S3, whether or not any of the symbols R1 displayed on the display windows 16 a to 16 c is changed after all the rotatable reels 56 a to 56 c are stopped. The slot machine 10 proceeds to Step S5 when the error occurrence condition is satisfied, or proceeds to Step S6 when the error occurrence condition is not satisfied.

In Step S5, the slot machine 10 stores error data indicating in which display window the symbol R1 that has been changed is displayed, and at which time point the symbol R1 was changed.

In Step S6, the slot machine 10 determines whether or not it is appropriate to start a subsequent unit game. The processing goes to Step S1 when it is determined to be appropriate to start the subsequent unit game, or goes to Step S3 when it is determined not to be appropriate to start the subsequent unit game.

Next, the configuration of the slot machine 10 will be described. FIG. 2 is a perspective view showing the slot machine 10 according to the embodiment of the present invention. The slot machine 10 includes a cabinet 11, a top box 12 disposed above the cabinet 11, and a main door 13. A display 16 is provided on the face of the cabinet 11 facing a player. Various component members including a controller 40 (see FIG. 6) for electrically controlling the slot machine 10, a hopper 44 (see FIG. 6) for controlling insertion, storage, and payouts of medals, the rotatable reels 53 a to 53 c, a case 83 (See FIG. 3), and the like are provided inside the cabinet 11.

Although this embodiment employs medals as an example of a game medium for executing games, the game medium are not limited only to medals. For instance, it is also possible to use coins, tokens, electronic money, and other electronic value information (credits) equivalent thereto as the game media.

The case 83 houses the rotatable reels 53 a to 53 c, the reel bands Q1 to Q3, bar code readers 54 a to 54 c (sensors), and stepping motors 56 a to 56 c. Now, a configuration of the rotatable reels 53 a to 53 c, the reel bands Q1 to Q3, the bar code readers 54 a to 54 c, and the stepping motors 56 a to 56 c will be described with reference to FIG. 2 to FIG. 5B. FIG. 4 is a perspective view showing the rotatable reels 53 a to 53 c and a surrounding structure thereof. FIG. 5A is an explanatory view showing the front surface of the reel band Q1, and FIG. 5B is an explanatory view showing the rear surface of the reel band Q1.

The rotatable reels 53 a to 53 c are housed in parallel with one another inside the case 83. The rotatable reel 53 a includes a disk 532 a, a ring member 533 a, and connectors 534 a.

The rotating shaft of the stepping motor 56 a is connected to the center 531 a of the disk 532 a. The ring member 533 a has the same radius as that of the disk 532 a. The ring member 533 a is set parallel to the disk 532 a, and the center thereof is opposed to the center 531 a of the disk 532 a. The connectors 534 a connect the disk 532 a to the ring member 533 a. The multiple connectors 534 a are provided at constant intervals. Accordingly, the disk 532 a, an outer circumferential section of the ring member 533 a and the connectors 534 a collectively constitute a peripheral surface of the rotatable reel 53 a. The rotatable reel 53 a is rotated when the stepping motor 56 a is driven. The rotating shaft of the stepping motor 56 a becomes the rotating axis of the rotatable reel 53 a.

The multiple symbols R1 are drawn on the front surface of the reel band Q1. Blanks are also treated as the symbols R1. Bar codes B1 are drawn on sections on the rear surface of the reel band Q1 opposed with the respective symbols R1 (i.e. the back sides of the symbols R1). Each bar code B1 specifies the symbol R1 drawn on the reverse side thereof. Accordingly, designs of the bar codes B1 are different from each other, depending on the symbols R1. The reel band Q1 is wound around the peripheral surface of the rotatable reel 53 a so as not to cause the bar codes B1 to overlap the connector 534 a. Moreover, the front end Q12 and a back end Q13 of the reel band Q1 are made to overlap each other, and the overlapped sections are bonded together. In this way, the front end Q12 and the back end Q13 of the reel band Q1 are bonded to each other. However, the reel band Q1 is not bonded to the rotatable reel 53 a. The reel band Q1 is rotated along with rotation of the rotatable reel 53 a. Some of the symbols R1 drawn on the reel band Q1 are displayed on the display window 16 a of the display 16.

The rotatable reel 53 a is rotated by driving the stepping motor 56 a. The bar code reader 54 a reads the bar code B1 drawn on the back side of the symbol R1 displayed in the middle column of the display window 16 a, and detects the symbol R1 displayed in the middle column of the display window 16 a according to the bar code B1 thus read out. The bar code reader 54 a performs this detection processing when a detection request signal is sent from a central processing unit (CPU) 106. The bar code reader 54 a outputs a detection result signal concerning the detected symbol R1 to the CPU 106.

The rotatable reels 53 b and 53 c have a similar configuration to the rotatable reel 53 a. The reel band Q2 has a similar configuration to the reel band Q2. The reel band Q2 is wound around a peripheral surface of the rotatable reel 53 b so as not to cause the bar codes B1 to overlap connectors 534 b of the rotatable reel 53 b. Moreover, the front end Q22 and a back end Q23 of the reel band Q2 are made to overlap each other, and the overlapped sections are bonded together. In this way, the front end Q22 and the back end Q23 of the reel band Q2 are bonded to each other. However, the reel band Q2 is not bonded to the rotatable reel 53 b. Layouts of the symbols R1 on the reel band Q2 are different from that on the reel band Q1. The reel band Q2 is rotated along with rotation of the rotatable reel 53 b. Some of the symbols R1 drawn on the reel band Q2 are displayed in the display window 16 b of the display 16.

The reel band Q3 has a similar configuration to the reel band Q1. The reel band Q3 is wound around a peripheral surface of the rotatable reel 53 c so as not to cause the bar codes B1 to overlap connectors 534 c of the rotatable reel 53 c. Moreover, the front end Q32 and the back end Q33 of the reel band Q3 are made to overlap each other, and the overlapped sections are bonded together. In this way, the front end Q32 and the back end Q33 of the reel band Q3 are bonded to each other. However, the reel band Q3 is not bonded to the rotatable reel 53 c. Layouts of the symbols R1 on the reel band Q3 are different from those on the reel bands Q1 and Q2. The reel band Q3 is rotated along with rotation of the rotatable reel 53 c. Some of the symbols R1 drawn on the reel band Q3 are displayed on the display window 16 c of the display 16.

The stepping motors 56 b and 56 c have a similar configuration to the stepping motor 56 a. Specifically, the rotatable reel 53 b is rotated when the stepping motor 56 b is driven, and the rotatable reel 53 c is rotated when the stepping motor 56 c is driven.

The bar code reader 54 b reads the bar code B1 drawn on the back side of the symbol R1 displayed in the middle column of the display window 16 b and detects the symbol R1 displayed in the middle column of the display window 16 b according to the bar code B1 thus read out. The bar code reader 54 b outputs a detection result signal concerning the detected symbol R1 to the CPU 106.

The bar code reader 54 c reads the bar code B1 drawn on the back side of the symbol R1 displayed in the middle column of the display window 16 c and detects the symbol R1 displayed in the middle column of the display window 16 c according to the bar code B1 thus read out. The bar code reader 54 c outputs a detection result signal concerning the detected symbol R1 to the CPU 106. The bar code readers 54 b and 54 c perform the detection processing when the detection request signal is sent from the CPU 106. A payline is formed with the middle column of the display window 16 a, the middle column of the display window 16 b, and the middle column of the display window 16 c. When a combination of the symbols R1 stopped on the payline is equal to a predetermined combination, a total medal count is increased by a predetermined number corresponding to the combination. The total medal count is a total number of medals that the slot machine 10 can pay to a player, which is stored in a random access memory (RAM) 110.

The main door 13 is openably and closably fitted to the cabinet 11, and the display 16 is disposed approximately in the center of this main door 13.

A total-medal-count display section 48 is provided in a lower left region of the display 16.

A medal insertion slot 21 for inserting the medals to be used for playing a game, and a bill validator 22 for identifying legitimate bills and for accepting legitimate bills are provided below the display 16. Various operation switches are provided to the vicinity of the medal insertion slot 21 and the bill validator 22.

A cash-out switch 23, a MAXBET switch 24, a BET switch 25, a spin repeat bet switch 26, and a start switch 27 are provided as the operation switches.

The BET switch 25 is for determining the number of medals to be bet on a unit game. One medal is bet on the unit game every time the BET switch 25 is pressed.

The spin repeat bet switch 26 is for betting the same number of medals as a precedent unit game on a current unit game.

The start switch 27 is for staring the unit game. The unit game will be started when this start switch 27 is pressed after the number of the medals bet for the unit game (which will be hereinafter referred to as a “bet number” as well) becomes equal to or more than 1.

The cash-out switch 23 is for paying out the medals in an amount equivalent to the total medal count. The medals to be cashed out are discharged from a medal payout opening 19 located at a lower part on a front face of the main door 13. The medals thus cashed out are collected in a medal tray 18.

The MAXBET switch 24 is for betting, with a single operation, the maximum number of medals (such as 30 medals) that the player can bet in one round of the unit game. These switches 23 to 27 output predetermined operation signals to the CPU 106 when operated by the player.

A foot display 34 is provided on the lower front face of the main door 13 and displays various images concerning the games of the slot machine 10. The images may include characters of the slot machine 10, for example. The medal payout opening 19 is provided below the foot display 34.

An upper display 33 is disposed on the front face of the top box 12. The upper display 33 includes a display panel and displays the number of medals to be paid out corresponding to combinations of the symbols R1, and the like.

Moreover, a speaker 29 and a lamp 30 are provided on the top box 12. A ticket printer 35, a card reader 36, a data display 37, and a keypad 38 are provided below the upper display 33. The ticket printer 35 prints a bar code for various coded data including the total medal count, date and time, the identification number of the slot machine 10, and the like on a ticket, and outputs the ticket as a bar-coded ticket 39.

The player is able to play with a different slot machine by allowing this slot machine to read the bar-coded ticket 39, and to exchange the bar-coded ticket 39 with bills and the like in a designated place in a game arcade (such as a cashier in a casino).

The card reader 36 is made to allow insertion of a smart card, to read data from the inserted smart card, and to write data into the smart card. The smart card is the card carried by the player, which stores data for identifying the player, data concerning a history of games played by the player, and so forth.

FIG. 6 is a block diagram showing an electrical configuration of the controller 40 provided in the slot machine 10 according to this embodiment and various instruments to be connected to the controller 40. The controller 40 of the slot machine 10 shown in FIG. 6 is a microcomputer, which includes an interface circuit group 102, an input-output bus 104, the CPU 106, a ROM 108, the RAM 110, a communication interface circuit 111, a motor driving circuit 51, a timer 52, a speaker driving circuit 122, a hopper driving circuit 124, and a display driving circuit 128.

The interface circuit group 102 is connected to the input-output bus 104. This input-output bus 104 executes input and output of data signals or address signals to and from the CPU 106.

The start switch 27 is connected to the interface circuit group 102. A signal outputted from this start switch 27 is converted into a predetermined signal by the interface circuit group 102 and is then transmitted to the CPU 106 through the input-output bus 104.

The BET switch 25, the MAXBET switch 24, the spin repeat bet switch 26, the cash-out switch 23, and an error data display switch 50 are connected to the interface circuit group 102. The respective signals outputted from these switches 25, 24, 26, 23, and 50 are supplied to the interface circuit group 102, converted into predetermined signals in this interface circuit group 102, and then transmitted to the CPU 106 through the input-output bus 104. The error data display switch 50 is provided inside the cabinet 11 so that the player cannot touch that switch. The error data display switch 50 is supposed to be operated by a staff member of a game arcade. When the error data display switch 50 is operated, an error presence checking request signal is outputted to the CPU 106 through the interface circuit group 102. Processing carried out by the CPU 106 corresponding to this signal will be described later.

In addition, the bill validator 22 and a medal sensor 43 are connected to the interface circuit group 102. The bill validator 22 identifies legitimate bills, accepts a legitimate bill when the bill is determined to be legitimate, and calculates the number of medals corresponding to the value of the bill. The bill validator 22 outputs a signal concerning the calculated number of medals to the CPU 106 through the interface circuit group 102. The CPU 106 increases the total medal count in response to the number of medals calculated by the bill validator 22 according to the signal sent from the bill validator 22.

The medal sensor 43 is for detecting the medals inserted into the medal insertion slot 21, which is provided in a medal insertion region of the medal insertion slot 21. A detection signal outputted from this medal sensor 43 is supplied to the interface circuit group 102, then converted into a predetermined signal in this interface circuit group 102, and then transmitted to the CPU 106 through the input-output bus 104. The CPU 106 increments the total medal count by one every time the signal is sent from the medal sensor 43.

The ROM 108 for storing a game execution program and various data and the RAM 110 functioning as a work area for the CPU 106 are connected to the input-output bus 104. Moreover, the communication interface circuit 111, the motor driving circuit 51, the timer 52, the hopper driving circuit 124, the speaker driving circuit 122, and the display driving circuit 128 are connected to the input-output bus 104.

The CPU 106 reads a game execution program and executes the unit game by taking acceptance of pressing the start switch 27 as a trigger. Hence, the game execution program is a program necessary for executing a unit game.

The communication interface circuit 111 is connected to a hall server or the like and transmits data such as a history of the plays executed by this slot machine 10 to the hall server. Moreover, the communication interface circuit 111 receives various data transmitted from the hall server.

The motor driving circuit 51 drives and stops the stepping motors 56 a to 56 c under control of the CPU 106. The display driving circuit 128 displays the total medal count on the total medal count display section 48 defined in the lower left region of the display 16.

The timer 52 measures a current time point. A value T of the current time point is increased as time goes further. The value T of the timer 52 is displayed by the second as the unit thereof.

The speaker driving circuit 122 outputs audio data to the speaker 29. Specifically, the CPU 106 reads the audio data stored in the ROM 108 and transmits the audio data to the speaker driving circuit 122 through the input-output bus 104. In this way, predetermined sound effects are outputted from the speaker 29.

The hopper driving circuit 124 outputs a payout signal to the hopper 44 when a cash-out occurs. Specifically, when a cash-out signal is inputted from the cash-out switch 23, the CPU 106 outputs a drive signal to the hopper driving circuit 124 through the input-output bus 104. In this way, the hopper 44 cashes out the medals corresponding to the total medal count.

FIG. 7 shows correlations between the symbols R1 detected by the bar code readers 54 a to 54 c and the time points of detection of the symbols R1 by the bar code readers 54 a to 54 c. The time points of detection of the symbols R1 by the bar code readers 54 a to 54 c are expressed by the values T of the timer 52. The values T of the timer 52 are expressed by T0, T1, T2, Tn (n is an integer) in ascending order.

The CPU 106 outputs the detection request signal to the bar code readers 54 a to 54 c at a time point when all the rotatable reels 53 a to 53 c are stopped (or to be more precise, at a time point when a stop completion signal is sent from the motor driving circuit 51) and acquires the value T of the timer 52. The value T of the timer 52 at this point is expressed as T0. Accordingly, the value T0 of the timer 52 indicates the time point when all the rotatable reels 53 a to 53 c are stopped. According to FIG. 7, at the time point when all the rotatable reels 53 a to 53 c are stopped, the bar code reader 54 a detects a “bell”, the bar code reader 54 b detects a “cherry”, and the bar code reader 54 c detects a “plum”.

Thereafter, the CPU 106 further outputs the detection request signals to the bar code readers 54 a to 54 c at given time intervals (such as every 0.5 (s)) from that time on. When the detection request signal is provided, the bar code readers 54 a to 54 c detect the symbols R1 displayed in the middle columns of the display windows 16 a to 16 c and output the detection result signals concerning the detected symbols R1 to the CPU 106. The CPU 106 links the contents of the detection result signals, i.e. the symbols R1 detected by the bar code readers 54 a to 54 c, with the value T of the timer 52, and stores the data in the RAM 110. The data formed by linking the symbols R1 detected by the bar code readers 54 a to 54 c with the value T of the timer 52 will be hereinafter referred to as correspondence data as appropriate.

Moreover, according to the correspondence data stored in the RAM 110, the CPU 106 judges whether the error occurrence condition is satisfied, the error occurrence condition being that any of the symbols R1 displayed on the display windows 16 a to 16 c is changed after the time point when all the rotatable reels 56 a to 56 c are stopped. When the error occurrence condition is satisfied, the CPU 106 generates the error data indicating on which display window the changed symbol is displayed and at which time point the symbol was changed, and stores the error data in the RAM 110. To be more precise, the CPU 106 generates the error data indicating the display window where the symbol R1 is changed and the value T of the timer 52 indicating the time point when the symbol R1 is changed, and stores the error data in the RAM 110. For example, when the correspondence data shows the correlations shown in FIG. 7, the symbol R1 displayed on the display window 16 a is changed at the time point when the value T of the timer 52 becomes equal to T2. Accordingly, the CPU 106 stores the error data indicating the display window 16 a and the value T2 of the timer 52 in the RAM 110.

When the CPU 106 receives the error presence checking request signal from the error data display switch 50, the CPU 106 judges whether or not the error data are stored in the RAM 110. When the error data indicating the display window 16 a and the value Tn of the timer 52 are stored in the RAM 110, the CPU 106 displays a character string “ERROR1-Tn” on the total medal count display unit 48. When the error data indicating the display window 16 b and the value Tn of the timer 52 are stored in the RAM 110, the CPU 106 displays a character string “ERROR2-Tn” on the total medal count display unit 48. When the error data indicating the display window 16 c and the value Tn of the timer 52 are stored in the RAM 110, the CPU 106 displays a character string “ERROR3-Tn” on the total medal count display unit 48. When error data are not stored, the CPU 106 does not display any of these character strings.

In this way, a staff member of the game arcade can recognize whether or not the error occurrence condition is satisfied. Moreover, when the error occurrence condition is satisfied, the staff member of the game arcade can recognize the display window in which the changed symbol R1 is displayed and at which time point the symbol was changed.

Next, main processing executed by the slot machine 10 will be described with reference to FIG. 8. When a power source is turned on, the slot machine 10 performs various initial setting processing and then repeatedly executes the main processing. The value of the timer 52 is set to 0 at the time point of turning the power source on and then starts increasing.

In Step S7, the CPU 106 judges whether a condition that a outcome of a previous unit game is present is satisfied, or more specifically, judges whether a condition that the correspondence data are stored in the RAM 110 is satisfied. The processing goes to Step S7-1 when this condition is satisfied, or goes to Step 11 when this condition is not satisfied. Since the correspondence data are absent at the time point immediately after tuning the power source on, the CPU 106 advances the processing to Step S11.

In Step S7-1, the CPU 106 acquires a value T of the timer 52 and judges whether a condition that the acquired value T of the timer 52 is equal to or above (Tα+0.5) is satisfied. The processing goes to Step S8 when this condition is satisfied, or goes to Step S11 when this condition is not satisfied. The value Tα is the largest value among the values T of the timer 52 indicated by the correspondence data.

In Step S8, the CPU 106 outputs the detection request signal to the bar code readers 54 a to 54 c. In response to the signal, the bar code readers 54 a to 54 c detect the symbols R1 displayed in the middle columns of the display windows 16 a to 16 c, generate the detection result signals concerning the detected symbols R1, and output the detection result signals to the CPU 106. The CPU 106 links the contents of the detection result signals, i.e. the symbols R1 detected by the bar code readers 54 a to 54 c, with the value T of the timer 52 acquired in Step S7-1, and stores the data in the RAM 110. In this way, the correspondence data are expanded.

In Step S9, according to the correspondence data stored in the RAM 110, the CPU 106 judges whether the error occurrence condition is satisfied, the error occurrence condition being that any of the symbols R1 displayed on the display windows 16 a to 16 c is changed after the time point when all the rotatable reels 53 a to 53 c are stopped. The CPU 106 advances the processing to Step S10 when the error occurrence condition is satisfied, or to Step S11 when the error occurrence condition is not satisfied.

In Step S10, the CPU 106 stores the error data, which indicate the display window where the symbol R1 is changed and the value T of the timer 52 indicating the time point when the symbol R1 is changed, in the RAM 110.

In Step S11, the CPU 106 judges whether a condition that a bet number stored in the RAM 110 is equal to or above 10 is satisfied. The processing goes to Step S12 when this condition is satisfied, or goes to Step S7 when this condition is not satisfied. The CPU 106 executes a bet number calculation processing as interrupt processing relative to the main processing. To be more precise, the CPU 106 calculates the bet number according to the signals provided from the switches 24, 25, and 26, and judges whether a condition that the calculated bet number is equal to or below the total medal count is satisfied. The CPU 106 stores the calculated bet number in the RAM 110 when this condition is satisfied, and reduces the total bet count by the amount equivalent to the calculated bet number. On the contrary, the CPU 106 invalidates and discards the calculated bet number when this condition is not satisfied.

In Step S12, the CPU 106 judges whether or not it is appropriate to start the unit game. To be more precise, the CPU 106 judges whether a condition that the start switch 27 is pressed, or namely, a condition that the given signal is sent from the start switch 27, is satisfied. The processing goes to Step S12-1 when this condition is satisfied, or goes to Step S7 when this condition is not satisfied.

In Step S12-1, the CPU 106 judges whether a condition that the correspondence data are stored in the RAM 110 is satisfied. The processing goes to Step S12-2 when this condition is satisfied, or goes to Step S13 when this condition is not satisfied.

In Step S12-2, the CPU deletes the correspondence data stored in the RAM 110 and resets the value of the timer 52 to 0. After the value is reset to 0, the timer 52 immediately restarts increasing the value.

In Step S13, the CPU 106 executes the unit game. To be more precise, the CPU 106 outputs a drive signal to the motor driving circuit 51. The motor driving circuit 51 starts driving the stepping motors 56 a to 56 c when the driving signal is sent from the CPU 106. In this way, the rotatable reels 53 a to 53 c start rotation, and the symbols R1 displayed on the display windows 16 a to 16 c start scrolling. Hence the unit game is started.

After a lapse of a certain time period (such as 10 (s)) from starting the unit game, the CPU 106 outputs a stop signal to the motor driving circuit 51. As the stop signal is sent from the CPU 106, the motor driving circuit 51 stops the stepping motors 56 a to 56 c. Accordingly, the rotatable reels 53 a to 53 c are stropped, and the symbols R1 to be displayed on the display windows 16 a to 16 c are stopped. In other words, the stopped symbols R1 are displayed in the respective columns of the display windows 16 a to 16 c. Hence the unit game is completed. After stopping all the stepping motors 56 a to 56 c, the motor driving circuit 51 outputs a stop completion signal to the CPU 106.

In Step S14, the CPU 106 determines the outcome of the unit game. To be more precise, the CPU 106 acquires the value T (=T0) of the timer 52 at the time point when the stop completion signal is sent from the motor driving circuit 51 (i.e. at the time point when all the rotatable reels 53 a to 53 c are stopped), and outputs the detection request signal to the bar code readers 54 a to 54 c at the same time. When the detection request signal is provided, the bar code readers 54 a to 54 c detect the symbols R1 displayed in the middle columns of the display windows 16 a to 16 c, and output the detection result signals corresponding to the detection results to the CPU 106. The CPU 106 links the contents of the detection result signals, i.e. the symbols R1 detected by the bar code readers 54 a to 54 c, with the acquired value T of the timer 52, and stores the data in the RAM 110. In this way, the correspondence data are generated, and the outcome of the unit game becomes definite.

In Step S15, the CPU 106 calculates a payout amount of medals according to the three symbols R1 indicated by the correspondence data generated in Step S14 (i.e. the symbols R1 displayed in the middle columns of the display windows 16 a to 16 c when all the rotatable reels 53 a to 53 c are stopped).

In Step S16, the CPU 106 provides a payout. To be more precise, the CPU 106 increases the total medal count in the amount equivalent to the payout amount calculated in Step S15. Thereafter, the CPU 106 terminates the main processing.

As described above, the slot machine 10 detects the symbols R1 according to the bar codes B1. Accordingly, it is possible to detect the positions of the symbols R1 accurately, or more specifically, the symbols R1 displayed in the middle columns of the display windows 16 a to 16 c. Moreover, the slot machine 10 repeatedly detects the symbols to be displayed in the middle columns of the display windows 16 a to 16 c after all the rotatable reels 53 a to 53 c are stopped and judges according to the detected symbols R1 whether or not any of the symbols R1 displayed on the display windows 16 a to 16 c is changed after the time point when all the rotatable reels 56 a to 56 c are stopped. Hence, the slot machine 10 can detect occurrence of accidental rotating operations of the rotatable reels 53 a to 53 c or intentional rotating operations of the rotatable reels 53 a to 53 c even after the original rotating operations of the rotatable reels 53 a to 53 c are completed.

Moreover, although the slot machine 10 has the configuration of winding the reel bands Q1 to Q3 around the rotatable reels 53 a to 53 c, the symbols R1 drawn on the reel bands Q1 to Q3 are detected directly according to the bar codes B1. Accordingly, it is possible to detect the symbols R1 accurately.

The slot machine 10 links the symbols R1 and the time points of detection of the symbols R1, and stores the data repeatedly after the time point when all the rotatable reels 53 a to 53 c are stopped. Accordingly, the slot machine 10 can also detect the time point of change of the symbol R1.

The slot machine 10 is configured to wind the reel bands Q1 to Q3 around the rotatable reels 53 a to 53 c and to attach only the front ends and the back ends of the reel bands Q1 to Q3 together. However, since the symbols R1 drawn on the reel bands Q1 to Q3 are detected directly according to the bar codes B1, it is possible to detect the symbols R1 reliably. In other words, even when rotation of the reel bands Q1 to Q3 is deviated from rotation of the rotatable reels 53 a to 53 c, it is still possible to detect the symbols R1 accurately.

First Modified Example

Next, a first modified example of the slot machine 10 will be described. As shown in FIG. 9, the slot machine 10 according to the first modified example includes a card slot 57 a and a memory card 57 b in addition to the configuration shown in FIG. 6. The card slot 57 a is connected to the interface circuit group 102 and is disposed inside the slot machine 10. The memory card 57 b is attachable to and detachable from the card slot 57 a. The CPU 106 can exchange data with the memory card 57 b when the memory card 57 b is connected to the card slot 57 a. To be more precise, the CPU 10 stores the above-described correspondence data in the memory card 57 b in addition to the RAM 110. The CPU 106 performs the above-described processing using the correspondence data that are stored either in the RAM 110 or in the memory card 57 b.

Accordingly, the slot machine 10 can detect occurrence of accidental rotating operations of the rotatable reels 53 a to 53 c and intentional rotating operations of the rotatable reels 53 a to 53 c even after the original rotating operations of the rotatable reels 53 a to 53 c are completed.

In addition, a staff member of a game arcade can recognize whether or not any of the symbols R1 is changed by taking the memory card 57 b out of the slot machine 10 and allowing a server 200 shown in FIG. 10 to read the correspondence data stored in the memory card 57 b.

Now, the server 200 and a surrounding structure thereof will be described with reference to FIG. 10. FIG. 10 is a block diagram showing the server 200 and the surrounding structure thereof. The server 200 includes a CPU 201, a RAM 202, and a ROM 203. In addition, a card slot 204, a display 205, and a keyboard 206 are connected to the server 200.

The CPU 201 displays on the display 205 the correspondence data stored in the memory card 57 b. The RAM 202 is used as a work area for the CPU 201. The ROM 203 stores a program and various data necessary for operations of the CPU 201. The card slot 204 is configured to allow attachment and detachment of the memory card 57 b and is connected to the CPU 201. The CPU 201 can exchange the data with the memory card 57 b when the memory card 57 b is connected to the card slot 204. In other words, the CPU 201 acquires the correspondence data from the memory card 57 b when the memory card 57 b is connected to the card slot 204, and displays the correspondence data on the display 205. The display 205 displays the correspondence data under control of the CPU 201. The keyboard 206 is used by the staff member of the game arcade to input various data. The keyboard 206 outputs the inputted data to the CPU 201. The data may include display request data for requesting display of the correspondence data, for example.

Next, operations of the server 200 will be described. When the staff member of the game arcade connects the memory card 57 b to the card slot 204 and inputs the display request data by use of the keyboard 206, the data are outputted from the keyboard 206 to the CPU 201. When the display request data are sent from the keyboard 206 to the CPU 201, the CPU 201 acquires the correspondence data from the memory card 57 b. Then the CPU 201 stores the data in the RAM 202 and displays the data on the display 205 at the same time.

In this way, the staff member of the game arcade can recognize whether or not any of the symbols R1 is changed.

Second Modified Example

Next, a second modified example of the slot machine 10 will be described. As shown in FIG. 11, in the slot machine 10 according to the second modified example, the reel band Q1 is bonded to the peripheral surface of the rotatable reel 53 a, i.e. to the outer circumferential section of the disk 532 a and the ring member 533 a as well as the connectors 534 a together. The reel bands Q2 and Q3 are also bonded to the peripheral surfaces of the rotatable reels 53 b and 53 c, respectively.

Even with this configuration, the slot machine 10 directly detects, according to the bar codes B1, the symbols R1 drawn on the reel bands Q1 to Q3. Accordingly, it is possible to detect the symbols R1 accurately. Moreover, the slot machine 10 can detect occurrence of accidental rotating operations of the rotatable reels 53 a to 53 c and intentional rotating operations of the rotatable reels 53 a to 53 c even after the original rotating operations of the rotatable reels 53 a to 53 c are completed.

Third Modified Example

Next, a third modified example of the slot machine 10 will be described. As shown in FIG. 12, the slot machine 10 according to the third modified example has different structures of the rotatable reels 53 a to 53 c from the structure shown in FIG. 4. Specifically, the rotatable reel 53 a includes the disk 532 a, the ring member 533 a, the connectors 534 a, and a peripheral surface member 535 a. The peripheral surface member 535 a is formed into a cylindrical shape, and the length from the central axis thereof to an outer peripheral surface thereof is equal to the length of the radius of the disk 532 a and the ring member 533 a. The peripheral surface member 535 a constitutes the peripheral surface of the rotatable reel 53 a. Multiple symbols R1 are drawn on the front surface of the peripheral surface member 535 a, and the bar codes B1 are drawn on the sections out of the rear surface of the peripheral surface member 535 a opposed with the symbols R1. The disk 532 a and the ring member 533 a are respectively provided to the end sections on both sides of the peripheral surface member 535 a. The connectors 534 a connect the disk 532 a and the ring member 533 a. The connectors 534 a contact the rear surface of the peripheral surface member 535 a so as not to overlap the bar codes B1. The disk 532 a, the ring member 533 a, the connectors 534 a, and the peripheral surface member 535 a are integrally formed. The rotatable reels 53 b and 53 c also have a similar configuration.

Even in this configuration, the slot machine 10 directly detects, according to the barcodes B1, the symbols R1 drawn on the reel bands Q1 to Q3. Accordingly, it is possible to detect the symbols R1 accurately. Moreover, the slot machine 10 can detect occurrence of accidental rotating operations of the rotatable reels 53 a to 53 c and intentional rotating operations of the rotatable reels 53 a to 53 c even after the original rotating operations of the rotatable reels 53 a to 53 c are completed.

Although the embodiment of the slot machine according to the present invention has been described above, it is to be noted that the embodiment and the modified examples described above are merely examples and will not limit the present invention. The concrete structures of the respective constituents of the present invention are subject to design changes when appropriate. Moreover, the effects stated in conjunction with the present invention merely describe some preferable effects to be achieved by the present invention, and the effects of the present invention are thus not limited only to those described in conjunction with the embodiment and the modified examples. For example, the number of the rotatable reels is not limited only to 3. Although the slot machine 10 is configured to detect the symbols R1 by utilizing the bar codes B1, the method of detecting the symbols R1 is not limited only to this configuration. For instance, magnetic tapes storing different data for each of the symbols R1 may be bonded to the rear surfaces of the reel bands Q1 to Q3 instead of the bar codes B1. In addition, magnetic heads may be provided instead of the bar code readers 54 a to 54 c so that the data on the magnetic tapes, i.e. the symbols R1 are detected by use of these magnetic heads. Alternatively, it is possible to drill punch holes in the sections of the reel bands Q1 to Q3 where the symbols R1 are drawn. Here, optical sensors may be provided instead of the bar code readers 54 a to 54 c so that the symbols R1 are detected by using these optical sensors. In this case, distribution of the punch holes varies depending on the symbols R1. When light is emitted from the optical sensors to the symbols R1, a fraction of the light is reflected by the reel bands Q1 to Q3 and returns to the optical sensors. Meanwhile, the remaining light passes through the reel bands Q1 to Q3 and does not return to the optical sensors. Consequently, intensity distribution of the reflected light to be detected by the optical sensor varies depending on the symbols R1. In this way, it is possible to detect the symbols R1. 

1. A slot machine comprising: a rotatable reel including a plurality of symbols drawn on a peripheral surface thereof and being rotatable and stoppable; a display adapted to display part of the symbols; a sensor configured to repeatedly detect the symbols displayed on the display at least after a stop of the rotatable reel; and a controller configured to (a) execute a unit game for rotating and stopping the rotatable reel, (b) determine an outcome of the unit game according to one of the symbols detected by the sensor at a time point of the stop of the rotatable reel, and (c) judge whether or not the one of the symbols displayed on the display is changed after the stop of the rotatable reel, according to the symbols repeatedly detected by the sensor after the stop of the rotatable reel.
 2. A slot machine comprising: a rotatable reel being rotatable and stoppable; a reel band wound on a peripheral surface of the rotatable reel and having a plurality of symbols drawn on the reel band; a display adapted to display part of the symbols; a sensor configured to repeatedly detect the symbols displayed on the display at least after a stop of the rotatable reel; and a controller configured to (a) execute a unit game for rotating and stopping the rotatable reel, (b) determine an outcome of the unit game according to one of the symbols detected by the sensor at a time point of the stop of the rotatable reel, and (c) judge whether or not the one of the symbols displayed on the display is changed after the stop of the rotatable reel, according to the symbols repeatedly detected by the sensor after the stop of the rotatable reel.
 3. A slot machine comprising: a rotatable reel being rotatable and stoppable; a reel band wound on a peripheral surface of the rotatable reel and having a plurality of symbols drawn on the reel band; a display adapted to display part of the symbols; a sensor configured to repeatedly detect the symbols displayed on the display at least after a stop of the rotatable reel; and a controller configured to (a) execute a unit game for rotating and stopping the rotatable reel, (b) store the symbols repeatedly detected by the sensor after the stop of the rotatable reel and time points of detections of the symbols by the sensor linking each other, (c) determine an outcome of the unit game according to at least one of the symbols linked to a time point of the stop of the rotatable reel among the stored symbols, and (d) judge whether or not the at least one of the symbols displayed on the display is changed after the stop of the rotatable reel according to the stored symbols.
 4. A slot machine comprising: a rotatable reel being rotatable and stoppable; a reel band wound on a peripheral surface of the rotatable reel and having a plurality of symbols drawn on the reel band; a display adapted to display part of the symbols; a sensor configured to repeatedly detect the symbols displayed on the display at least after a stop of the rotatable reel; a removable memory storing the symbols repeatedly detected by the sensor after the stop of the rotatable reel and time points of detections of the symbols by the sensor linking each other; and a controller configured to (a) execute a unit game for rotating and stopping the rotatably reel, (b) determine an outcome of the unit game according to at least one of the symbols linked to a time point of the stop of the rotatable reel among the symbols stored in the memory, and (c) judge whether or not the at least one of the symbols displayed on the display is changed after the stop of the rotatable reel according to the symbols stored in the memory.
 5. The slot machine according to any one of claims 2 to 4, wherein the one end and the other end of the reel band are fixed together.
 6. The slot machine according to any one of claims 2 to 4, wherein the reel band is fixed to the peripheral surface of the rotatable reel.
 7. A method of controlling a slot machine, the method comprising the steps of: executing a unit game for rotating and stopping a rotatable reel including a plurality of symbols drawn on a peripheral surface; displaying part of the symbols on a display; repeatedly detecting the symbols displayed on the display at least after a stop of the rotatable reel; determining an outcome of the unit game according to one of the symbols detected by the sensor at a time point of the stop of the rotatable reel; and judging whether or not the one of the symbols displayed on the display is changed after the stop of the rotatable reel, according to the symbols repeatedly detected by the sensor after the stop of the rotatable reel.
 8. A method of controlling a slot machine, the method comprising the steps of: executing a unit game for rotating and stopping a rotatable reel including a reel band wound on a peripheral surface of the rotatable reel and having a plurality of symbols drawn on the reel band; displaying part of the symbols on a display; repeatedly detecting the symbols displayed on the display at least after a stop of the rotatable reel; determining an outcome of the unit game according to one of the symbols detected by the sensor at a time point of the stop of the rotatable reel; and judging whether or not the one of the symbols displayed on the display is changed after the stop of the rotatable reel according to the symbols repeatedly detected by the sensor after the stop of the rotatable reel.
 9. A method of controlling a slot machine, the method comprising the steps of: executing a unit game for rotating and stopping a rotatable reel including a reel band wound on a peripheral surface of the rotatable reel and having a plurality of symbols drawn on the reel band; displaying part of the symbols on a display; repeatedly detecting the symbols displayed on the display at least after a stop of the rotatable reel; storing the symbols detected in the detecting step and time points of the detections linking each other; determining an outcome of the unit game according to at least one of the symbols linked to a time point of the stop of the rotatable reel among the stored symbols; and judging whether or not the at least one of the symbols displayed on the display is changed after the stop of the rotatable reel according to the stored symbols.
 10. A method of controlling a slot machine, the method comprising the steps of: executing a unit game for rotating and stopping a rotatable reel including a reel band wound on a peripheral surface of the rotatable reel and having a plurality of symbols drawn on the reel band; displaying part of the symbols on a display; repeatedly detecting the symbols displayed on the display at least after a stop of the rotatable reel; storing in a removable memory the symbols detected in the detecting step and time points of the detections; determining an outcome of the unit game according to at least one of the symbols linked to a time point of the stop of the rotatable reel among the symbols stored in the memory; and judging whether or not the at least one of the symbol displayed on the display is changed after the stop of the rotatable reel according to the symbols stored in the memory.
 11. The method according to any one of claims 8 to 10, wherein the one end and the other end of the reel band are fixed together.
 12. The method according to any one of claims 8 to 10, wherein the reel band is fixed to the peripheral surface of the rotatable reel. 